On Monday, the Italian narrowly dodged a spill by Alberto Contador that left the two-time Tour champion with a fractured shin. Nibali went on to barrel past a panting breakaway rider to win a fog-and-rain coated, up-and-down Stage 10 and recover the yellow jersey that he had lost only a day earlier.
It didn't come easy.
"This was the hardest stage I've ever done in a Grand Tour, with seven climbs and so many crashes," said Nibali.
Contador's mishap has given this 101st edition of cycling's greatest event a dubious distinction of being the first in recent memory to force out its two top stars to crash injuries. Five stages earlier, reigning champ Chris Froome quit with a broken wrist and hand sustained in a string of spills.
As the race enters its first rest day on Tuesday, Nibali — who has already won the Spanish Vuelta and Italian Giro — looks on his way to winning his first Tour with just under two weeks to go.
When Stage 10 began, many race pundits — and Nibali himself — expected Contador to try to erase his 2 1/2 minute deficit to the Italian by attacking on the ride to the finish atop La Planche des Belles Filles ski resort. As FDJ.FR team manager Marc Madiot put it: "This is the day for Contador to put Nibali into trouble."
Instead, it was Contador having the problems.
The 31-year-old Spaniard took a hard tumble in a high-speed downhill run in the Vosges mountains. After riding about 18 kilometres in pain, the Tinkoff-Saxo Bank team leader finally gave up. He put his foot down, got off his bike, wiped his eyes and got into a team car. An X-ray later showed a shin fracture.
Nibali said he had been ready for a "duel".
"I already had a good lead and I was ready to fight in a big duel with Alberto," he said. "Crashes are part of the sport. I've crashed myself many times in the past too. It's a pity that the Tour has lost two major protagonists."
The Astana team leader regained the lead from France's Tony Gallopin — who had taken the yellow jersey off him a day earlier — in the 161.5-kilometre trek from eastern Mulhouse to the steep finish at La Planche des Belles Filles.
With a final burst of speed in the last two kilometres, Nibali overtook breakaway rider Joaquim Rodriguez. By the end, Nibali crossed 15 seconds ahead of France's Thibaut Pinot in second and Spain's Alejandro Valverde in third, a further five seconds behind.
The Italian recovers the yellow jersey that he wore for seven days after he won the second stage in the hills of northern England. Overall, he leads Richie Porte of Australia by 2 minutes, 23 seconds, and Valverde, who is third, 2:47 back.
"My legs felt good. I knew the last three kilometres were the toughest, and that's when I accelerated," said Nibali, sucking his thumb in a tribute to his young daughter as he finished. "I thought Rodriguez would follow but he seemed to have trouble."
A string of crash injuries has meant that the Tour will have a first-time winner this year. Andy Schleck, the 2010 Tour winner, dropped out before Stage 4 following a crash injury a day earlier, though the Luxembourg rider said before the race that he wasn't in good enough shape to contend this year.
According to his spokesman, Contador said he wasn't exactly sure what caused the crash — which happened while he was speeding downhill at over 70 kph about halfway through the stage. Contador began the stage in ninth place overall — 4 minutes, 8 seconds back of Gallopin.
"He explained to me just a few minutes ago that he (hit) a stone or a hole in the road or something — and he crashed," Contador spokesman Jacinto Vidarte told The Associated Press by phone during the stage. "He couldn't do anything about it."
TV images showed thick streams of blood pouring from Contador's right knee after the crash, his hip was scraped up, and the back of his jersey torn. Team director Bjarne Riis rushed over and bandaged the knee. Philippe Mauduit, a team sporting director, said initial X-rays showed that a Contador had a fractured shin.
Contador then sat back down on the grass bank and changed his left shoe as riders weaved through the narrow gap between him and his bicycle. After several minutes, he got back in the saddle of a new bike, and three teammates who had dropped back escorted him to try to make up lost time as the peloton pulled away up the Col du Platzerwaswel mountain pass.
The Spaniard rode for about another half-hour, clearly in pain, and finally stopped, got off, wiped his eyes and climbed into a team car.
Nibali said he was riding next to Contador, and almost went down himself.
"I feared that the Tour might be over for me too," the Italian said. "There were a lot of risks today, and I'm really sorry for Alberto Contador. I was right behind him and luckily I was able to avoid him. It was on a descent. The road wasn't in great condition.
"I don't know what happened, but it was just incredible," said Nibali. "He fell right in front of me and was rolling on the floor. We must have been going about 60 kilometres per hour."
There were crashes elsewhere.
Italian rider Michele Scarponi — Nibali's Astana teammate — sustained a heavy crash coming down from the penultimate climb up to Col des Chevreres. He misjudged a turn and thudded into a protective crash barrier, flipping over his bike and colliding with a spectator, who was unhurt. Scarponi was able to continue riding.
British rider Geraint Thomas also crashed but kept racing with blood pouring out of his left elbow.
The race resumes Wednesday with a slightly hilly 187.5-kilometre route from Besancon to Oyonnax in eastern France. Stage 11 will feature four moderate climbs toward the end.
The three-week race ends on the Champs-Elysees in Paris on July 27.
Eds: AP Sports Writer Jerome Pugmire in Plancher-les-Mines, France, contributed to this report.